Bill Turbit was a convicted child molester who accidentally sexually assaulted a child while on drugs and was subsequently registered as a sex offender.
When a boy in Turbit's neighborhood, Ryan Davies, was raped and murdered, Turbit became the prime suspect. The SVU detectives found several inconsistencies in Turbit's alibi and arrested him. Detectives eventually discovered evidence that exonerated him. However, police psychiatrists who evaluated Turbit ruled that he should not be released even if he was innocent of Ryan's murder; they found him to be still sexually dangerous, and recommended that he be civilly committed.
Just after he was cleared of all charges, Turbit was inexplicably shot to death outside the courthouse by Ryan's father Terry. After Turbit's death, detectives discovered that he had been framed by the real killers, Jimmy G. and Mike D. (SVU: "Uncivilized")